Foxbat
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- Jan 2, 2011
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Hi Evereyone, I have a late 2010 D40 STX (140KW) and have been having trouble with the electrical system. The alternator output sits a 14.4V when the engine has just been started but after a few minutes of driving, it drops back to 12.1 and stays there most of the time. Every now and then it will go back upto 14.4 for a few minutes and then drops off again back to 12.1. I have done some investigation into the cause including having it back at nissan twice to find out why.
The alternator on these new models is equipped with a sensing arrangement that reduces the alternator output when the computer feels that the battery has had enough charge. The idea is that the alternator load on the engine is reduced and thus reduces the load on the engine somewhat in an effort to increase the fuel efficiency. The problem I have found is that the battery does not charge to anywhere near full enough. My aux battery was charging to 11.5V as it is connected via an isolator which is only 'on' after the start battery received it's recovery charge. Since the alternator then dropped its output voltage to 12.1, the isolator decoupled and no charge was getting to the aux battery.
The FIX,
The alternator has an internal regulator which is what the computer (CAN command line) controls. This is done by turning 'down' the regulator via the alternator input 'green' wire. Simply cut this wire and there you have it. The alternator is now a constant 14.4V output. Well, if you were like me, you would install and electrical plug that will enable you to convert back to standard wiring if necessary. Now I have done it, I will be watching intently over the next few days to make sure I don't let any smoke out.
Hope this helps somebody out.
Regards to all. Foxy.
The alternator on these new models is equipped with a sensing arrangement that reduces the alternator output when the computer feels that the battery has had enough charge. The idea is that the alternator load on the engine is reduced and thus reduces the load on the engine somewhat in an effort to increase the fuel efficiency. The problem I have found is that the battery does not charge to anywhere near full enough. My aux battery was charging to 11.5V as it is connected via an isolator which is only 'on' after the start battery received it's recovery charge. Since the alternator then dropped its output voltage to 12.1, the isolator decoupled and no charge was getting to the aux battery.
The FIX,
The alternator has an internal regulator which is what the computer (CAN command line) controls. This is done by turning 'down' the regulator via the alternator input 'green' wire. Simply cut this wire and there you have it. The alternator is now a constant 14.4V output. Well, if you were like me, you would install and electrical plug that will enable you to convert back to standard wiring if necessary. Now I have done it, I will be watching intently over the next few days to make sure I don't let any smoke out.
Hope this helps somebody out.
Regards to all. Foxy.